Flexible sheet agglomerate utilizable in foundry

ABSTRACT

AN INSULATING SHEET FOR FOUNDRY PRACTICE, SUCH AS AN INGOT MOLD LINING, IS IN THE FORM OF A FLEXIBLE SHEET OF SAND AND VEGETABLE FLOUR AGGLOMERATED WITH A BINDER, AND OPTIONALLY ALSO AN EXOTHERMIC MATERIAL AND ONE OR MORE INORGANIC INSULATING MATERIALS. THE SHEET HAS A THICKNESS OF 2 TO 12 MM. AND HAS ADHESIVE ON ONE SIDE TO HOLD IT TO THE MOLD. THE SHEET HAS A BEVEL ON AT LEAST ONE EDGE, THAT FACES AWAY FROM THE SIDE THAT BEARS THE ADHESIVE, THEREBY TO AVOID FORMATION OF SHOULDERS ON THE INGOT THAT WOULD ROLL OUT TO IMPERFECTIONS.

3,567,564 FLEXIBLE SHEET AGGLOMERATE UTILIZABLE IN FOUNDRY Lars Rydberg, Uranus Vager 8, Skalby, Sweden N Drawing. Filed July 13, 1967, Ser. No. 653,023 Claims priority, application Monaco, July 14, 1966, 632.67.602; June 7, 1967, 49 Int. Cl. B22d 7/10; B32b 1/04 U.S. Cl. 161-44 1 Claim ABSTRACT OF THE DISCLOSURE An insulating sheet for foundry practice, such as an ingot mold lining, is in the form of a flexible sheet of sand and vegetable flour agglomerated with a binder, and optionally also an exothermic material and one or more inorganic insulating materials. The sheet has a thickness of 2 to 12 mm. and has adhesive on one side to hold it to the mold. The sheet has a bevel on at least one edge, that faces away from the side that bears the adhesive, thereby to avoid formation of shoulders on the ingot that would roll out to imperfections.

There is in metallurgy, in steel-making in foundry practice, etc. a great number of applications requiring an input of heat and (or) a thermal insulation and (or) the use of a refractory, or even the intervention of products having analogous properties.

Until now, very different means have been used for obtaining the desired result. This is why, in the case of heat treatment of metals or of metallic pieces, or for the thermal stabilization of certain products, like plastic materials, the pieces or products to be treated are. generally placed in a furnace. This requires a special installation and, in certain cases, special means for establishing and maintaining inside the furnace or treating chamber a non-oxidizing atmosphere, for example. Moreover, for the heat treatment of certain parts of large size pieces, special installations are necessary for delaying the heating of the parts concerned. In each case, if the piece or part is to undergo gradual cooling, an immobilization of the furnace or of the treating installation results.

In steel-making, it is common practice to use, in ingotmolds, means which, through an exothermic or insulating effect, delay the solidification of the steel at the head of the ingot, in order to compensate, with steel that has remained in a liquid state or that is undergoing a partial refusion, the contraction that occurs at the time of solidification, and, in this way, to fill up possible. pipes.

The same principle is applied currently in foundry practice.

For this purpose, it is usual to provide extensions made of cast iron lined with refractory bricks and constituting a reserve of liquid steel, liner plates being able to be applied against the inside walls of the ingot mold, or else apparatuses permitting the setting up, by molding and tamping, of a suitable lining on the inside wall of the ingot mold.

The purpose of the invention is to make it possible to obtain a product usable directly and in a particularly simple way for these various applications, as well as for still other applications, each time that the characteristics of heat input and (or) thermal insulation and (or) refractory properties must be obtained, as technicians will readily understand.

The invention is exemplified practically, as a new industrial product, in an agglomerate in the form of a flexible or deformable sheet that can be used for applications of heat treatment, insulation and (or) application of refractories, constituted by the combination of at United States Patent 0 Patented Mar. 2, 1971 least one active substance providing the desired exothermic and (or) insulating and (or) isothermic and (or) refractory effect with at least one binding agent retaining in the assembly a plastic or semi-plastic character.

The active substances that can be incorporated with this sheet are well known. For this purpose, once can use mainly all of the materials used currently for the manufacture of liner plates for ingot molds or for the setting up of linings by molding and tamping. In the case of applications requiring an exothermic effect, it will be best to use the materials used currently in aluminothermic reactions, and the invention is not limited to the incorporation of one or more particular materials with the sheet. In the case of insulating or refractory applications, one can use very fine sand, dolomite, chamotte, vermiculite, a material of vegetable origin like wood flour, artificial insulating materials like perlite, a blown blast furnace slag, etc. Here, too, the invention is not limited to the use of a particular substance, since technicians can establish, from data well known at the present time, a composition giving the desired result each time.

The. binding agent or agents used for the constitution of this agglomerate in the form of a flexible or deformable sheet are advantageously synthetic resins capable of retaining a plastic or semi-plastic character in the assembly. It is easy to determine, among the resins known at the present time, those capable of achieving the desired bond between the particles of active substance, having a sufficient thermal resistance, retaining a plastic or semi-plastic state after their partial or complete polymerization, and whose state does not change too rapidly through aging.

A suitable binding agent can be formed, for example by a polyester giving rubber polymers, by a polystyrene or by a composition containing linseed oil, a copal resin and tricresyl phosphate.

The uses of the agglomerate, in the form of a flexible or deformable sheet, thus obtained are many.

For the heat treatment of pieces, for example metal pieces that have to undergo annealing, tempering or hardening, or of determined parts of large size pieces, it is suflicient to surround the piece or the part of the piece involved with an agglomerate in sheet form according to the invention containing one or more active substances determined depending upon the particular treatment desired, and to fix this agglomerate in place, for example by means of a simple adhesive strip. Such an agglomerate may contain, for example, an exothermic substance, preferably next to its surface in contact with the piece or the part of the piece to be treated, and an insulating substance next to the other face. The action of the exothermic substance first heats the piece or the part of the piece to the required temperature, and the insulating substance insures a slow cooling compatible with the treatment carried out. The agglomerate in sheet form can then closely surround the piece to be treated, for example a tube or pipe, which specifically excludes the oxidizing action of the air which would otherwise come in contact with the part treated.

In the case of hardening, such an agglomerate can bring the piece to the required temperature, this piece then being airor oil-cooled, for example, in an ordinary way.

An agglomerate in sheet form according to the invention can also be used to effect welds on pieces as a result of the pronounced exothermic effect that can be obtained.

Another important use of the agglomerate according to the invention is its application in steel making or in foundry. In this case, the sheetform agglomerate of the desired composition can, to advantage, be provided on its face that is to be directed towards the ingot mold with an adhesive coating or with one or more fixing elements,

preferably adhesive in nature. It can then be fixed in place, before the casting is done, by simple application against the wall of the ingot mold or other mold. In the case where fixing elements are provided, they can be constituted by adhesive strips provided on the suitable face of the agglomerate and capable of holding it against the wall of the ingot mold.

In addition to its ease of placement and use, an exotherniic and (or) insulating and (or) refractory and (or) isothermic agglomerate in sheet form, which can be used in steel making or in founding, offers still other advantages.

Thus, according to the invention, this agglomerate can be given a very slight thickness, from 2 to 12 millimeters for example, which is distinctly less than the usual thicknesses of rigid liner plates and of cast and tamped linings. For this reason, the sheet obtained can extend over a greater height inside the ingot mold, which has a very considerable influence on the progress of the solidification of the ingot, making this solidification more gradual from the base and modifying the usual profile of the isotherms of solidification. Thus, such a sheet may extend over a height representing up to 25-30% of the height of the ingot, while until the present time, the linings used were able to involve only the upper part of the ingot mold so that their action was not felt in depth.

In addition, the slight thickness of the sheet prevents the production on the ingot of a shoulder whose presence is disadvantageous and which causes a large end that must be rejected as a result of the problems which arise at the time of rolling. Moreover, the use of such a sheet, forming an ultra-thin lining, increases the volume of liquid steel in the feedhead and retards its solidification.

According to another special feature, the active exother-mic substance of the agglomerate can have a character of auto-combustion, so that it may disappear during use, and the composition can then'undergo deaggregation, which upon being compacted outwardly, permits the still liquid steel substantially to fill the space previously occupied by the sheet.

Such a special feature is also very advantageous in foundry practice.

According to still another feature of the invention, the active substance or substances of the sheet is agglomerated by means of two binding agents or groups of binding agents one of which behaves to provide the required cohesion and suppleness while the other one provides the necessary resistance to heat.

The first binding agent or group of binding agents may comprise one or several resins of the polyester type and more particularly polyvinyl acetate or one or several copolymers having a polyvinyl acetate base.

Alternatively the first binding agent or group of binding agents may be also constituted by other types of resins capable of furnishing equivalent results, particularly by epoxide resins or by natural or synthetic rubbers.

This first binding agent or group of binding agents is more particularly active while the sheet is laid inside an ingot mold, especially for permitting said sheet to adapt itself to the eventual curvature of the ingot mold without any risk of breakage or damage.

The second binding agent or group of agents may be constituted notably by a binder of the general type used in foundry practice, such as core oil or else by a binder for foundry sand. A particularly satisfactory solution of the problem involved consists in using to that effect linseed oil.

This second binding agent or group of binding agents has for its purpose to impart to the sheet the necessary resistance during and after the casting operation owing to the resultant advantages derived from its good behavior towards heat.

Owing to this combination of binding agents, there is obtained in the sheet in the dry state some elasticity or possibility of distortion which is operative to compensate 4 inside the sheet itself and between the sheet and the ingot mold for the differences in heat expansion, thereby avoiding the risk of a shearing effect on the fibres of said sheet.

According to a further advantageous feature of the invention, when the sheet is secured by sticking, the composition of the adhesive is also calculated so as to impart to the dry adhesive some elasticity or possibility of distorsion so as to compensate in the adhesive layer for the differences in heat expansion between the sheet and the in'got mold in such a way as here again to avoid the sheet fibres being shorn. To that effect, several adhesives having different characteristics may be admixed.

Preferably, adhesives of the phenol-formaldehyde or urea-formaldehyde type are utilizable.

It is known that in the steel-making industry, the ingot molds may have during their use widely different temcratures ranging for example from ambient temperature up to 200 to 300 C. Now commonly used adhesives have drying periods which vary within wide ranges depending upon the temperature to which they are subjected and it will be therefore understood that unduly long drying periods are troublesome in the present case because they do not permit the metal to be cast immediately after the application of the sheet. In order to remedy this disadvantage, and according to a still further feature of the invention, use is made for securing the sheet of an adhesive capable of drying at a low temperature and there is added to it, preferably when using it, of a catalyst or accelerator permitting quick setting to be obtained. The casting of the metal can thus be achieved in a very short time following the application of the sheet.

However the sheet may be also held in the desired position on the ingot mold wall during setting or drying of the adhesive by a nailing process.

According to a still further feature of the invention, the agglomerate sheet presents on at least some of its edges a bevelled portion which still further reduces the shoulder formed in the ingot and thus avoids any risk of formation of flaws or hollows when rolling the ingot to shape and thus avoids the concomitant disadvantages, particularly when it is dropped. Such a bevelled portion may be simply prvoided on the side edges of the sheet so as to eliminate the aforesaid shoulder in the horizontal cross section of the ingot which corresponds with the rolling stresses when such sheets are simply fixed to the ingot faces and not to its corners. It seems useful, however, to provide a bevelled portion not only on the lower edge of the sheet but also on its upper edge.

Thus it is seen that the agglomerate in sheet form according to the invention is of particularly practical use in various industrial fields and solves many problems, the solution to which was provided, until now, only by the use of distinctly more complex methods.

Below will be given, in a non-limiting capacity, several examples of compositions of sheet-form agglomerates according to the invention, the parts and the percentages being given by weight.

EXAMPLE NO. 1

The composition below can be used for the preparation of an agglomerate designed to carry out an annealing operation:

Granulated aluminum (No. screen)-=428% and particularly 8% Chamotte, 0.1 to 2 mm.4075% and particularly 73% Potassium chlorate, water content 4%'010% and particularly 4% Cryolite05 and particularly 3 Red iron oxide-O-lS and particularly 9% Manganese dioxide015% and particularly 3% 5 EXAMPLES NO. 2-6

These examples refer to a composition of agglomerate in sheet form that can be used as insulating material:

Examples No.

Magnesia. Bauxite \egetable flour (wood, paper, corn etc.)

Venniculi Asbestos EXAMPLES NO. 7-10 These examples refer to a composition of agglomerate in sheet form that can be used as exothermic product:

Examples N0.

Granulated aluminum (No.140 screen) 20 15 2-30 7 Granulated aluminum (N 10 5 2-30 67 Iron scale (iron oxide)- 10 10 116 Red iron oxide 2 10 1-12 Potassium carbonate 4 3 1-8 Cryolite 1 1 12 Manganese dioxide.-- 3 4 -10 Ochre earth 0-30 Fine extra-siliceous sand. 0-10 Ordinary san 40 0-15 Ohamotte 4 0-50 Vegetable flour (wood, paper, etc.) 0-12 11 Perlite. 010 Vnr-mimrlitn 0-10 Changes can be made in the working examples described, in the area of technical equivalencies, without deviating from the invention.

What is claimed is:

1. An insulating member for use in foundry practice, comprising a thin flexible and deformable sheet of sand and vegetable flour agglomerated with a flexible binder, said sheet having a thickness of 2 to 12 mm., and a layer of adhesive on one side of said sheet for securing the same to a metal member, said sheet having at least one beveled margin that faces away from the side of the sheet that bears the adhesive.

References Cited UNITED STATES PATENTS 2,195,254 3/1940 Miller 161-208 3,183,562 5/1965 Moore 249200UX 3,221,382 12/1965 Haw 249201UX 3,344,838 10/1967 Nouveau 249200X 3,456,914 7/ 1969 Konrad 249201 DOUGLAS J. DRUMMOND, Primary Examiner U.S. Cl. X.R. 

